To provide a joint drive device which is light-weight and compact while being able to cope with changes in the position and posture of an instantaneous rotary shaft of a joint.SOLUTION: A joint drive device 10 comprises: a rotation drive mechanism 20； a first connection member 33 and a second connection member 44 with a slide mechanism； a first link member 30 attached to the rotation drive mechanism and rotated about a first axis X0 by the rotation drive mechanism； a second link member 40 passively and slidably connected to the first link member along a second axis A orthogonal to the first axis via the first connection member； and a holding member 50 for holding a foot part 3, which is passively and slidably connected to the second link member along a third axis B orthogonal to the second axis via the second connection member. The first connection member and the second connection member passively slide according to the rotation of the rotation drive mechanism. The first connection member is disposed on the distal side from the foot part.SELECTED DRAWING: Figure 1【課題】関節の瞬間回転軸の位置及び姿勢の変化に対応可能でありながら、軽量で小型な関節駆動装置を提供する。【解決手段】関節駆動装置１０が、回転駆動機構２０と、摺動機構を備えた第１接続部材３３及び第２接続部材４４と、回転駆動機構に取り付けられ、該回転駆動機構によって第１軸線Ｘ０回りに回転する第１リンク部材３０と、第１接続部材を介して、第１軸線に対して直交する第２軸線Ａに沿って受動的に摺動可能に第１リンク部材に対して接続された第２リンク部材４０と、足部３を保持する保持部材５０であって、第２接続部材を介して、第２軸線に対して直交する第３軸線Ｂに沿って受動的に摺動可能に第２リンク部材に対して接続された保持部材と、を具備し、回転駆動機構の回転に応じて、第１接続部材及び第２接続部材が受動的に摺動し、第１接続部材が、足部よりも遠位側に配置されている。【選択図】図１
